JP2001356730A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device which can control display failure caused by existence of electrically uncontrollable defective dots by a preferable method, and moreover realize reduction in cost for the correction of the failure, and further realize simplification of the circuit configuration. SOLUTION: The display device is provided with a calculation circuit for controlling a signal to be applied to dots 106, 107 in the neighborhood of a defective dot 105 so that a difference between a color obtained by coloring the neighbor dots 106, 107 and an original color of the defective dot 105 and the neighbor dots 106, 107 based on the input signals becomes small, and the calculation circuit decides a signal value to be applied to the green dot 107 of the neighbor dots 106, 107 by a calculation based on a function obtained from a correlation between an original input signal to the defective dot 105 and a signal value to be applied to the green dot 107 according to the original input signal, and thereafter decides a signal value to be applied to the blue dot 106.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device (hereinafter referred to as LCD) and a plasma display device (hereinafter referred to as PDP) having a function of making it difficult to see electrically uncontrollable dots (hereinafter referred to as defective dots). And a display device having a pixel structure.

[0002]

2. Description of the Related Art In a display device such as an LCD or a PDP in which three color dots constituting fine pixels are spatially arranged, a defective dot is generated at a rate of one out of several millions due to its manufacturing method. Exists. Since the intensity of light of such a dot cannot be freely controlled, a color cannot be freely generated at a pixel associated with the dot. Therefore, even if such a defect is present at a very small rate, such as one in several million pixels, it is a serious problem in image quality. For this reason, the display device has to be strict in sorting the shipment, which raises the overall cost and hinders the spread of the display device.

FIG. 16 is an explanatory view schematically showing a display device having a defect. In FIG. 16, 201 is red, 2
02 is a blue dot, 203 is a green dot, and 204 is a black matrix portion. The color arrangement is a so-called vertical stripe arrangement. In FIG. 16, the hatched portions represent the shining portions.
This corresponds to a case where the surface of the display device when one surface is blue is greatly enlarged. In other words, the following description will be made on the assumption that only the blue dot 202 shines on one surface.

In FIG. 16, it is assumed that the blue dot 205 is defective and this dot is a black dot.
In this case, this dot cannot be lit, although it should be lit blue on one side. Therefore, color discontinuity occurs in this portion, and visual image quality deteriorates.

For such defective dots, it is a fundamental measure to improve the manufacturing technique itself. For example, there is a method for improving the precision and cleanliness of a manufacturing apparatus.

[0006] Alternatively, there is a method of correcting a circuit pattern or the like for a defective dot found in an inspection after manufacturing. For defective dots for which measures can be taken after manufacturing, measures such as cutting the circuit or sintering the circuit with a laser device or the like according to the situation of the defective dot to make the defective dot invisible are taken. ing.

Conventionally, as described above, two approaches have been mainly adopted, namely, improvement of the manufacturing technique itself and measures taken after the manufacture have been taken to reduce the defective rate and reduce the overall cost.

[0008]

However, the conventional countermeasure method has a problem that a large cost is required for the countermeasure. For example, introducing a facility with a high degree of cleanness requires an extremely large introduction cost, and maintaining the cleanness also requires a large cost.

Also, there are the following problems regarding measures such as a method of cutting or sintering a circuit with a laser device or the like to make defective dots difficult to see.

First, there is a problem that the result of the measure cannot be freely selected. In other words, since the measures taken by the laser device have only two degrees of freedom, that is, burning or sintering the circuit, it is only possible to select whether to release the defective dot permanently or conduct it. Therefore, it is only possible to take a countermeasure against either a state in which light is completely emitted (defective bright spot) or a state in which light is not completely emitted (defective black spot). Defects that can be made non-defective by such measures are originally very limited defects, and this technique alone cannot be used to significantly reduce the overall defect rate.

Next, there is a problem that the throughput of the countermeasure is extremely low. This means that it takes a long time to analyze the contents of the defect, determine which circuit should be burned or sintered, and execute it. For this reason, even if the above measures are taken, it cannot be said that defects can be efficiently reduced.

[0012] From the above two problems, there is a problem that even if measures are taken by the laser device, it is far from far beyond to significantly reduce the overall failure rate.

[0013] Eventually, the improvement of the manufacturing technique or the countermeasure with the laser device or the like requires a considerable cost, which raises the problem of raising the overall cost.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to suppress display defects due to the presence of defective dots that cannot be electrically controlled in a desirable manner, and to reduce cost for defect correction. It is an object of the present invention to provide a display device which realizes the above, and which also realizes simplification of a circuit configuration.

[0015]

In order to solve the above-mentioned problems, a display device according to the present invention includes a plurality of pixels, each of which performs a display operation by using dots of at least three colors. In order to compensate for a display defect due to the presence of a defective dot that cannot be controlled, a signal to be applied to a plurality of dots in the vicinity of the defective dot, a color obtained by coloring the plurality of dots, the defective dot, and the Control means for controlling the difference from the original color based on the input signals of the plurality of dots to be smaller, the control means sets a signal value to be applied to one of the plurality of dots, Determined by an operation based on a function obtained from the correlation between the original input signal of the defective dot and the signal value to be applied to the one dot according to the input signal. It is characterized by determining by calculation a signal value applied to the other dot.

According to the above invention, the difference between the color obtained by coloring a plurality of dots near the defective dot and the original color based on the input signals of the defective dot and the plurality of dots becomes smaller. In this way (preferably, the difference is minimized), the signals applied to the plurality of dots are controlled. As a result, a state substantially equal to the original color of the defective dot can be created in the vicinity of the dot, and display defects due to the defective dot can be suppressed. Further, according to the present invention, the above-mentioned respective problems which have occurred in the case of the countermeasure by the conventional laser device do not occur.

Further, the control means should apply a signal value to be applied to one of the plurality of dots to the original input signal of the defective dot and to the one of the plurality of dots in accordance with the input signal. It is determined by an operation based on a function obtained from the correlation with the signal value. Therefore, the signal value applied to one dot can be determined by a relatively simple calculation,
Thereby, the circuit configuration can be simplified.

The present invention can be suitably applied to, for example, a liquid crystal display device, but is not limited thereto, and can be similarly applied to other display devices such as a plasma display device and an electroluminescence display device. In addition, the present invention is not limited to a display device that performs color display using one display panel, but includes a plurality of panels corresponding to each color, and a projection display device that synthesizes light from these panels to perform color display ( For example, the present invention can be similarly applied to a liquid crystal projector).

It is preferable that an approximate straight line obtained from a correlation between an original input signal of the defective dot and a signal value to be applied to the one dot in accordance with the input signal is used as the function, Thereby, the operation can be simplified.

As the function, it is conceivable to use a function approximated to a shape closer to the above-mentioned correlation obtained from an experimental result by using an LUT (look-up table) or the like, in addition to the approximation line.

The color difference is determined by CIE (1976) L *
It is preferable that the color difference is represented by a * b * color difference value.

Further, in the display device according to the present invention, the control means preferably controls the sum of the brightness of the plurality of dots to be substantially equal to the sum of the original brightness based on the input signals of the defective dot and the plurality of dots. It is preferable that the signals applied to the plurality of dots be controlled. As a result, a state substantially equal to the original brightness of the defective dot can be created in the vicinity of the dot, and display defects due to the defective dot can be suppressed.

Further, in the display device according to the present invention, it is preferable that the slope of the approximate straight line is determined based on the value of the input signal of the one dot. The slope of the approximated straight line can be determined.

In the display device of the present invention, it is preferable to use an approximate value consisting of 0 and 1/2 ⁿ (where n is an integer of 0 or more) as the slope of the approximate straight line. The configuration can be further simplified.

In the display device according to the present invention, the control means determines a slope of the approximate straight line based on a value of the input signal of the one dot, and multiplies the slope by a value of the input signal of the defective dot. A first circuit for calculating the value
A second circuit for adding a value of the input signal of the one dot to the value calculated by the circuit, and calculating and outputting a signal value to be applied to the one dot, preferably such a simple circuit. According to the configuration, a signal value to be applied to one dot can be determined.

Further, in the display device of the present invention, it is preferable that the first circuit is realized by a bit shift circuit, whereby the circuit configuration can be further simplified.

[0027] In the display device of the present invention, the control means further calculates a signal value to be applied to the other dots, so that each of the input signals of the defective dot and the plurality of dots is calculated. It is preferable to include a third circuit for calculating a power and multiplying based on a predetermined value, and a circuit configuration including the third circuit can determine a signal value to be applied to the other dot.

Further, in the display device of the present invention, it is preferable that the third circuit is realized by a look-up table, whereby the circuit configuration can be further simplified.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
This will be described below with reference to FIGS.

FIG. 1 is a diagram for explaining a situation around a defective dot in the display panel of this embodiment.

In FIG. 1, 101 is red, 102 is blue,
Reference numeral 103 denotes green dots, and reference numeral 104 denotes a black matrix portion, in which the color arrangement is a so-called vertical stripe arrangement. In FIG. 1, the hatched portion indicates a glowing portion, and FIG. 1 corresponds to a case where the surface of the display device when one surface is red is greatly enlarged. In other words, the following description will be made on the assumption that only the red dot 101 shines on one surface.

Here, a dot is a minimum unit of a color for displaying each color such as RGB, and a pixel is a minimum display unit of an image including each one of the dots such as RGB. Pixels can display color and brightness.

In FIG. 1, it is assumed that a red dot 105 is a defective dot and this dot is a black dot. In this case, this dot cannot be illuminated, although it should be illuminated red all over. Therefore,
Color discontinuity occurs in this portion, and visual image quality deteriorates.

In this embodiment, the defective red dot 1
By controlling signals applied to the blue dot 106 and the green dot 107, which are the dots adjacent to the dot 05, display defects due to the defective dot 105 are reduced. That is, when the unavoidably generated red defective dot 105 becomes a black point, the signal applied to the blue dot 106 and the green dot 107 which are adjacent to the defective dot is controlled to control the original brightness of the defective dot 105. A state approximately equal to the size and color is created in the vicinity of the dot to reduce visual disturbance. In FIG. 1, the signals controlled in this manner are applied, and the blue dot 106 and the green dot 107 are applied.
Is shown by hatching.

FIG. 2 shows visual spatial frequency characteristics. This example is described in Sakata and Isono, "Spatial Frequency Characteristics of Chromaticity in Vision," Journal of the Institute of Television Engineers of Japan, Vo1.31, No.
1, pp. 29-35 (1976), where the horizontal axis indicates the spatial frequency, that is, the fineness of the image, and the vertical axis indicates the relative response. The parameters of the three curves in the graph indicate the conditions of the measured color.

According to the figure, it can be seen that the visual light and dark response has a band approximately three to five times wider than the red-green and yellow-blue responses.

An example of measuring the visual spatial frequency response is:
There are many other than Sakata et al., But in each case, the bandwidth of the light / dark response is about several times wider than the color response. That is, it can be said that, in general, the visual characteristics are such that a small change in color is hardly recognized by a small change in brightness.

Therefore, in this embodiment, the blue dot 106
And the sum of the luminance of the green dots 107
In addition, the color obtained by coloring the blue dot 106 and the green dot 107 and the defective dot 105 and the neighboring dots are substantially equal to the sum of the original luminances based on the input signals of the neighboring dots 106 and 107. The blue dot 106 and the green dot 107 are set so that the difference from the original color based on the input signals 106 and 107 becomes smaller (preferably, the difference is minimized).
To control the signal applied to. Specifically, each dot 10
Based on the input of the color signals 5 to 107, an arithmetic circuit 3 described later
02, the signals to be applied to the neighboring dots 106 and 107 are determined by performing the following calculation.

The input luminance which is the original luminance based on the input signals of the defective dot 105, the green dot 107 and the blue dot 106 is defined as (R1, G1, B1). Assuming that the subsequent (after defect correction) luminance is (R2, G2, B2), in this embodiment, the luminance values G2, B2 corresponding to the signals applied to the green dot 107 and the blue dot 106 respectively are as follows. Ask.

That is, any input luminance (R1, G1,
With respect to B1), the luminance after control is substantially equal to
Further, (R1, G1, R1, G1, and R2) are set so that the difference between the original color including the dots 105 to 107 and the color after control becomes smaller (preferably, the difference is minimized).
(G2, B2) corresponding to (B1) is obtained. This is obtained by dividing the algorithm into two stages as follows.

1) First, input luminance (R1, G1, B1)
, The optimum G2, that is, the G2 at which the luminance difference ΔL * = 0 and the color difference ΔE * is minimized (min) is obtained.

2) Next, with respect to the obtained G2, ΔL * = 0
B2 that satisfies is obtained.

In this embodiment, CIE (1976) L * a * b * color difference is used for the color difference ΔE *. The CIE (1976) L * a * b * color values, which are the basis of the CIE (1976) L * a * b * color difference, are also described in Japanese Patent Application Laid-Open No. 9-329495, etc., and are well known. Value.

Here, first, the following experiment was conducted in order to examine the optimum tendency of G2 calculated in 1). That is, changes in G2 when G1 and B1 were fixed and R1 was changed were examined. Then, as shown in FIGS. 3 to 7, the R1-G2 graph showing the relationship between the value of R1 and the corresponding optimal value of G2 is the same when G1 is equal regardless of the value of B1. It turned out that a tendency was seen. That is, the optimal G2 is G1, R1
, And almost does not depend on B1.

FIG. 3 shows a case where G1 = 0, and FIG.
5 when G1 = 64, and FIG. 6 when G1 = 128.
7 shows the case where G1 = 192, and FIG. 7 shows the case where G1 = 255. For each color of RGB, 8 bits (256
(Gradation).

Therefore, based on the above experimental results, an approximate straight line is derived from the R1-G2 graph corresponding to each value of the input value G1, and G2 is obtained from the approximate straight line. That is, G2 is obtained by linear approximation from the input values G1 and R1, and more specifically, G2 is obtained by the following equation (1).

G2 = a (G1) × R1 + G1 (1) Here, a (G1) indicates the slope of the approximate straight line. In the present embodiment, the slope a (G1) is a value of G1 and a corresponding slope a (G1) as shown in FIG.
This is determined from the G1-a (G1) graph showing the relationship with the value of 1). Note that the slope a (G1) of the approximate straight line
3 to 7 as shown in Table 1 below, for example.
Are obtained, and the G1-a (G1) graph of FIG. 8 is derived from such experimental results.

[0048]

[Table 1]

As described above, of G2 and B2, G2
Is determined by an operation based on a function obtained from the R1-G2 graph (here, the above equation (1) indicating an approximate straight line). Therefore, the value of G2 can be determined by a relatively simple operation, and the circuit configuration can be simplified.

As will be described later, the value of G2 may be obtained by using an approximate value consisting of 0 and 1/2 ⁿ (where n is an integer of 0 or more) as the gradient a (G1). . In this case, the circuit can be realized by the bit shift circuit, and the circuit configuration can be further simplified.

Next, as a method of obtaining B2 in the above 2), B2 is obtained by the following equation (2) derived from the definition equation of CIE (1976) L * a * b * color value. That is, ΔL * = 0⇔L ₁ * = L ₂ * ⇔Y ₁
= Y ₂ , R ₂ = 0,

[0052]

(Equation 1)

Here, γ is the value of the exponent part when the relationship between the input signal to the display device and the display characteristic which is the output of the display device is expressed by an exponential function, and depends on the target display device or display signal. Will be different values. Γ _R , γ _G , γ
_B indicates γ of each color of RGB. Y is C
IE (1976) is one of the tristimulus values in the definition formula of L * a * b * color value, and Y _R , Y _G , and Y _B indicate Y of each of the RGB colors.

The G2 and B2 obtained as described above are respectively assigned to the green dot 1 adjacent to the red defective dot 105.
07 and the blue dot 106,
A state substantially equal to the original brightness and color of the defective dot 105 is created near the defective dot 105, and the defective dot 10
5 can be suppressed.

In the above example, the defective dot is red (R). However, when the blue (B) or green (G) dot is a defective dot, the input signal is , The signals to be applied to two dots adjacent to the defective dot may be sequentially obtained by calculation.

For example, FIG. 14 shows adjacent pixels ST. If the blue dot 113 is a defective dot, two adjacent pixels ST
An example in which a signal applied to the signal 114 is controlled will be described.

The input luminance which is the original luminance based on the input signals of the green dot 112, the defective dot 113 and the red dot 114 is defined as (G1, B1, R1), and the above control for the green dot 112, the defective dot 113 and the red dot 114 is performed. Assuming that the subsequent luminance (after defect correction) is (G2, B2, R2), in this example, the luminance values G2, R2 corresponding to the signals applied to the green dot 112 and the red dot 114 respectively are as follows: It is determined by dividing the algorithm into stages.

1) First, input luminance (G1, B1, R1)
, The optimum G2, that is, the G2 at which the luminance difference ΔL * = 0 and the color difference ΔE * is minimized (min) is obtained.

2) Next, with respect to the obtained G2, ΔL * = 0
R2 that satisfies is obtained.

More specifically, it is determined as follows.

For a blue (B) defect, the optimal G2 is G
G2 is determined by the following equation (3), as in the case of the red (R) defect described above, because it depends only on 1, B1 and does not substantially depend on R1.

G2 = b (G1) × B1 + G1 (3) Here, b (G1) indicates the slope of the approximate straight line as in the case of a (G1), and can be derived from experimental results and the like.

Next, as a method of obtaining R2 in the above 2), R2 is obtained by the following equation (4) derived from the definition equation of CIE (1976) L * a * b * color value. That is, ΔL * = 0⇔L ₁ * = L ₂ * ⇔Y ₁
= Y ₂ , B ₂ = 0,

[0064]

(Equation 2)

The G2 and R2 obtained as described above may be applied to the green dot 112 and the red dot 114, respectively.

In the present embodiment, CIE (1976) L *
Although the calculation was performed based on the a * b * color values, the present invention is not limited to this. For example, CIE (197)
6) The calculation may be performed based on the L * u * v * color value, the CIELab97s color value, or the like, and basically any color value indicating a color perceived by humans may be used.

In this embodiment, not only the color difference but also the luminance difference, the sum of the luminance of two adjacent dots is the sum of the original luminance based on the input signals of the defective dot and the two adjacent dots. The signal applied to two adjacent dots is controlled so as to be substantially equal to (that is, the luminance difference ΔL * = 0). However, only the color difference is considered, and this difference is The neighboring dot application signal may be controlled so as to be small.

In this embodiment, as the function obtained from the R1-G2 graph, the above equation (1) indicating an approximate straight line is used. However, the function is not limited to such an approximate straight line. A function approximated to an original graph (the relationship between R1 and the optimum G2 for this) using an up table) may be used.

For example, as an equation for obtaining G2, in the above equation (1), G2 = a (G1) × R1 + G1 and R1 is approximated by a linear expression (that is, linear approximation).
G2 = a ₂ (G 1) × R ₁ ² + a ₁ (G 1) × R ₁ + G 1 G 2 = a ₃ (G 1) × R 1 ³ + a ₂ (G 1) × R 1 ² + a
_By approximating with a higher-order polynomial such as ₁ (G1) × R1 + G1 (ie, curve approximation), as can be seen from FIGS. 3 to 7, the error can be reduced (to a form closer to the original value). Can be.
Here, the coefficients a ₁ , a ₂ , a _3, etc. are functions of G1 and can be obtained by experiments or the like.

Next, the circuit configuration of this embodiment will be described.

FIG. 9 is a block diagram showing a circuit configuration of the present embodiment. In the figure, 301 is an address detection circuit, 302 is an arithmetic circuit (control means), 303 is a switch circuit, 304 is a display panel, and 305 is a delay circuit.

It is assumed that the display panel 304 has a defective dot at the address (x, y) shown in the figure.

The address detection circuit 301 determines the current display position based on the synchronization signal, and applies a flag signal (switching signal) to the switch circuit 303 at the timing of displaying the position (x, y) of the defective dot. Specifically, such a circuit can be realized by a simple counter.

In order to cause the address detection circuit 301 to perform such an operation, the position of a defective dot is separately detected, and a counter is preset so that a flag signal is output when the address of the defective dot is reached. deep.
The address detection of the defective dot will not be described in detail here, but it is sufficient to simply specify the defective dot by performing a full lighting test and set the address.

The switch circuit 303 includes a delay circuit 305
The input signal that has passed through and the output of the arithmetic circuit 302 are input, the output of the arithmetic circuit 302 is output at the timing of the flag signal, and otherwise, the input signal that has passed through the delay circuit 305 is output as it is. .

In this embodiment, the arithmetic circuit 302 calculates the signal values G2 and B2 to be applied to the two dots 106 and 107 near the defective dot 105 by using the above equation (1).
The calculation of (2) is performed. As specific hardware,
For example, a CPU, a DSP, or the like can be used. The configuration of the arithmetic circuit 302 will be described later in detail.

The delay circuit 305 includes an arithmetic circuit 302
In order to adjust the calculation time delay in the above, an appropriate time delay is applied to the input signal and the synchronization signal. However,
If the time delay of the arithmetic circuit 302 is negligibly small, a configuration in which the delay circuit as shown in FIG. 10 is omitted may be employed.

Next, referring to FIG.
Will be described. FIG. 11 is a more detailed circuit diagram of a red (R) defective portion of the arithmetic circuit 302. As shown in the figure, an arithmetic circuit 302 includes circuits 401, 405, and 409 for performing the operation of the above equation (1), and circuits 402 to 404, 406 to 408, and 410 for performing the operation of the above equation (2).
415. Note that in the configuration in FIG. 11, the circuit 401 and the circuit 405 correspond to a first circuit. Also,
The circuit 409 corresponds to the second circuit, and the circuits 402 to 404.
406 to 408 correspond to the third circuit. Each of the circuits 402 to 404, 411, and 415 is a circuit that calculates a power using an LUT (lookup table).

G1 is input to the circuit 401, and the corresponding gradient a (G1) is calculated and output. The circuit 405 is a multiplier, which receives R1 and a (G1) and outputs a value of a (G1) × R1. Circuit 409
Is an adder, which receives G1 and the value of a (G1) × R1 and outputs a value of a (G1) × R1 + G1. This value is output from the arithmetic circuit 302 as G2.

On the other hand, R1 is input to the circuit 402,
The value of (R1 / 255) raised to the power of γ _R is output. This value and Y _R are input to the multiplier 406, and Y _R × (R 1/25
5) The value of γ _R raised is output.

Similarly, G1 is input to the circuit 403, and a value of (G1 / 255) raised to the γ _G power is output. This value and Y _G are input to the multiplier 407, and Y _G × (G1 /
255) is output as the value of the γ _G power. Also, the circuit 404
, B1 is input, and a value of (B1 / 255) raised to the γ _B power is output. This value and the Y _B are inputted to the multiplier 408, the value of the multiplication gamma _B of Y _B × (B1 / 255) is output.

Each output from multipliers 406-408 is sent to circuit 410. The circuit 410 is an adder, adds the output values from the multipliers 406 to 408, and outputs the added value to the subtractor 413.

On the other hand, G2 which is the output from the adder 409 is input to the circuit 411, and γ _{G of} (G2 / 255)
The value of the power is output. This value and the Y _G are inputted to the multiplier 412, the value of the multiplication gamma _G of Y _G × (G2 / 255) is output. This value is sent to the subtractor 413.

In the subtractor 413, the addition from the adder 410 is performed.
The value obtained by subtracting the value from the multiplier 412 from the calculated value is calculated.
And output to the divider 414. In the divider 414
Is Y _BAnd the value from the subtractor 413 are input,
The value from 413 to Y_BIs output. This value
Is sent to the circuit 415.

In the circuit 415, a value obtained by multiplying the value of the value from the divider 414 to the 1 / γ _B power by 255 is calculated and output. The output value from the circuit 415 is output from the arithmetic circuit 302 as B2.

The circuit configuration of the arithmetic circuit 302 is shown in FIG.
The configuration is not limited to the configuration shown in FIG. In FIG. 12, an arithmetic circuit 30 having a more simplified configuration is shown.
2 is shown. In this example, the arithmetic circuit 302
Are circuits 501 and 505 that perform the operation of the above equation (1);
Circuits 502 to 504 and 506 for performing the operation of the above equation (2)
To 509. Note that in the configuration in FIG. 12, the circuit 501 corresponds to a first circuit. The circuit 505 corresponds to a second circuit, and the circuits 502 to 504 correspond to a third circuit. The circuits 502 to 504, 507, 509
Is a circuit that collectively performs calculations such as exponentiation and multiplication using an LUT or the like.

The circuit 501 which is a bit shift circuit includes:
R1 and G1 are input, and a gradient a (G
1) multiplied by R1 to calculate a value a (G1) × R1;
Is output. The circuit 505 is an adder, and G1 and a
(G1) × R1 and a (G1) × R1 +
The value of G1 is output. This value is output from the arithmetic circuit 302 as G2.

On the other hand, R1 is input to the circuit 502,
The value of Y _R × (R 1/255) raised to the power of γ _R is calculated and output. Similarly, G1 is input to the circuit 503 and Y1 is input to the circuit 503.
_{The value of G} × (G1 / 255) raised to the γ _G power is output. Also, B1 is input to the circuit 504, and Y _B × (B1 /
The value of 255) raised to the power of γ _B is output.

Each output from the circuits 502 to 504 is sent to a circuit 506. The circuit 506 is an adder, adds each output value from the circuits 502 to 504, and outputs the added value to the subtractor 508.

On the other hand, G2 which is the output from the adder 505 is input to the circuit 507, and Y _G × (G2 / 255)
Is output to the power of γ _G. This value is sent to the subtractor 508.

In the subtracter 508, a value obtained by subtracting the value from the circuit 507 from the added value from the adder 506 is calculated and output to the circuit 509. The circuit 509 calculates and outputs a value obtained by multiplying the value obtained by dividing the value from the subtractor 508 by Y _B to the 1 / γ _B power by 255. This circuit 5
The output value from 09 is output from the arithmetic circuit 302 as B2.

In the configuration example shown in FIG. 12, the bit shift circuit 501 is used as the first circuit. In this case, 0 and （ ⁿ (where n
Is an integer of 0 or more). For example, if n = 2, as shown in FIG. 8, a (G1)
Is limited to any one of 0, 1/2, and 1/4, and the circuit 501 outputs 1 when a (G1) = 1/2.
In the case of a bit, a (G1) = 1/4, it can be realized by a 2-bit bit shift circuit. Thus, FIG.
In the configuration of 2, the gradient a (G1) is 0 and ２
^An approximate value consisting of the value of ⁿ is used.
Can be realized by a simple bit shift circuit.

In the configuration example shown in FIG.
Circuits 2 to 504, 507, and 509 collectively include a circuit for calculating a power and the like, a multiplier, and the like, and are configured in one LUT. A simpler circuit configuration is realized as compared with the configuration in FIG. I have.

In the above configuration, the inclination a (G1) and
And 0 and 1/2ⁿThe approximate value of
However, in addition to this, a value of 0 and a gradient a (G1) are
Two ⁿ(Where n is an integer of 1 or more) approximate values
May be used. For example, n = 2
And the value of G1 is divided into four regions as shown in FIG.
And the average value of a (G1) in each region (shown by a dotted line)
) Is defined as a (G1) corresponding to G1 in that area.
It is. However, with this configuration, the circuit
Not a shift circuit, but a look-up table (LU
T).

The present invention can be suitably applied to, for example, a liquid crystal display device. However, the present invention is not limited to this. If the display device has a pixel structure and data signals are digitally processed, the plasma display device (PDP) ) And other display devices such as an electroluminescence display device (EL). In addition, the present invention is not limited to a display device that performs color display using one display panel, but includes a plurality of panels corresponding to each color, and a projection display device that synthesizes light from these panels to perform color display ( For example, the present invention can be similarly applied to a liquid crystal projector).

In the present embodiment, the display panel is RGB.
Although the vertical stripe arrangement is used, the present invention is not limited to this, and can be similarly applied to display panels having other arrangements such as a delta arrangement and a mosaic arrangement.

In the present embodiment, as described above, the color obtained by coloring the blue dot 106 and the green dot 107 and the original color based on the input signals of the defective dot 105 and the dots 106 and 107 in the vicinity thereof are described. The signals applied to the blue dot 106 and the green dot 107 were controlled so that the difference was smaller (preferably, the difference was minimized).

In addition, the color obtained by coloring a plurality of dots in the vicinity of the defective dot is the difference between the original color of the pixel including the defective dot and the original color of one or more pixels in the vicinity of the pixel. The signals applied to the plurality of dots may be controlled so that the values are closer to the average color (preferably, the difference is minimized).

For example, as shown in FIG. 13, the color obtained by coloring two dots 602 and 603 adjacent to the defective dot 601 is different from the original color of the pixel T including the defective dot 601 and the color of the pixel T. The signals applied to the two dots 602 and 603 may be controlled so that the values become closer to the average color of the original colors of the two adjacent pixels SU.

In this case, the arithmetic circuit 302 first calculates the average L *, a *, and b * of these three pixels STU based on the input of each RGB signal of the adjacent pixels STU. L
* (Average), a * (average), and b * (average) are calculated.

Thereafter, the arithmetic circuit 302 performs the following arithmetic operation. That is, when the blue dot is defective, the blue output is set to 0 and the obtained L * (average), a *
Green and red, which provide color values closest to (average) and b * (average), are output values.

In the following, the above calculation in the arithmetic circuit 302 will be described in more detail, taking as an example the case where the blue (B) dot is defective.

The original signal values of the pixels S, T, and U are respectively represented by (R _S1 , G _S1 , B _S1 ), (R _T1 , G _T1 ,
B _T1 ), (R _U1 , G _U1 , B _U1 )
The signal values applied to each pixel are represented by (R _S2 , G _S2 ,
B _S2 ), (R _T2 , G _T2 , B _T2 ), (R _U2 , G _U2 , B _U2 )
And

The original color values of the S, T, and U pixels are represented by (L * _S1 , a * _S1 , b * _S1 ), (L
* _T1 , a * _T1 , b * _T1 ), (L * _U1 , a * _U1 , b * _U1 )
And the actual color value of each pixel of S, T, U is
(L * _S2 , a * _S2 , b * _S2 ), (L * _T2 , a * _T2 , b *
_T2 ), (L * _U2 , a * _U2 , b * _U2 ).

Then, first, in the arithmetic circuit 302,
Under the condition of 8 bits (256 gradations), the following CIE (1
976) Based on the definition formulas (5) and (6) of the L * a * b * color values, the original color values of the S, T, and U pixels (L
* _S1 , a * _S1 , b * _S1 ), (L * _T1 , a * _T1 , b
* _T1 ) and (L * _U1 , a * _U1 , b * _U1 ).

[0106]

(Equation 3)

[0107]

(Equation 4)

Next, in the arithmetic circuit 302, S.T.U3
Original color value of pixel average (L * _avg1 , a * _avg1 , b *
_avg1 ) is calculated based on the following equation.

L * _avg1 = (L * _S1 + L * _T1 + L * _U1 ) / _3a * _avg1 = (a * _S1 + a * _T1 + a * _U1 ) / _3b * _avg1 = (b * _S1 + b * _T1 + b *) _U1 ) / 3 Then, the arithmetic circuit 302 obtains output signals to the dots 602 and 603, that is, G _T2 and R _U2 as follows.

The actual color value (L
* _Avg2 , a * _avg2 , b * _avg2 ) are respectively _expressed as L * _avg2 = (L * _S2 + L * _T2 + L * _U2 ) / 3 a * _avg2 = (a * _S2 + a * _T2 + a * _U2 ) / _3b * _Avg2 = (b * _S2 + b * _T2 + b * _U2 ) / 3.

Here, in order to make the average luminance equal before and after correction (before and after control), L * _avg1 = L * _avg2 (7) In this case, it is a blue (B) dot defect and the control adjustment is performed. since only the output signal to the dot 602, 603 to the variable of the output signal value is only two G _T2, R _U2. Therefore, from the above equation (7), R _U2 can be represented as a function of G _T2 .

The output average color value is closest to the original average color value, that is, | a * _{avg2-
a * avg1 |, | b *} avg2 -b * avg1 | like is minimized, determines the value of G _T2.

When the value of G _T2 is obtained, R _U2 can be obtained from the above equation (7).

The green and red output values G thus obtained are
_By applying _T2 and _RU2 to two dots 602 and 603 adjacent to the defective dot 601, the defective dot 6
01, the pixel T including the defective dot 601
Alternatively, a color matching the original color can be displayed in the vicinity of the pixel T, and the defective dot 601 becomes very inconspicuous.

Although the present embodiment controls signals applied to two dots adjacent to a defective dot, the present invention is not limited to this. It is also possible to control the applied signals to two dots near the non-adjacent defective dot.

Further, it is also possible to control the applied signal to three or more dots in the vicinity of a defective dot instead of two dots.

For example, a case where four dots near defective dots are controlled will be described with reference to FIG. In this example, when the R dot 114 of the pixel T is a defective dot,
It is assumed that the luminance difference ΔL * is minimized and corrected by controlling the four dots of the G / B dots 112 and 113 of the pixel S and the G and B dots 115 and 116 of the pixel T.

Here, the original inputs to the RGB dots of the pixel S and the RGB dots of the pixel T are (R _S1 ,
G _S1 , B _S1 ) (R _T1 , G _T1 , B _T1 ), and output to each dot is (R _S2 , G _S2 , B _S2 ) (R _T2 , G _T2 , B _T
T2 ), as in the above equation (5),

[0119]

(Equation 5)

The same applies to Y _Si , Y _Ti , Z _Si , and Z _Ti .

From the above equation (6),

[0122]

(Equation 6)

L * _Ti , a * _Si , a * _Ti , b
* _Si and b * _Ti can be similarly defined.

Then, the original color value of the average of the S · T2 pixels is obtained.
(L *_avg1, A *_avg1, B *_avg1) Is L *_avg1= (L *_S1+ L *_T1) / 2 a *_avg1= (A *_S1+ A *_T1) / 2 b *_avg1= (B *_S1+ B *_T1) / 2, and the actual color value (L *_avg2,
a *_avg2, B *_avg2) Is L *_avg2= (L *_S2+ L *_T2) / 2 a *_avg2= (A *_S2+ A *_T2) / 2 b *_avg2= (B *_S2+ B *_T2) / 2. Therefore, the same operation as the above operation in the arithmetic circuit 302 is performed.
Like, L *_avg2-L *_{av g1}= 0 and | a *
_avg2-A *_avg1|, | B *_avg2-B *_avg1| Is the smallest
G_S2, B_S2, G_T2, B_T2Is calculated, and
Output to dots 112, 113, 115, 116 respectively
And it is sufficient.

As described above, the number of dots to be controlled may be three or more.

[0126]

As described above, the number of additional circuits for configuring the present invention is small. In the present invention, by adding such a small circuit, it is possible to use a panel that has been discarded because the number of defective dots has exceeded the reference number in the past. The greater the number, the greater the cost reduction effect as a whole.

Needless to say, mechanical processing using a laser device becomes unnecessary. In this measure, the content of the defect is analyzed,
To determine which circuit should be burned or sintered, and to implement it,
There is a problem that the throughput of the measure is extremely low.

On the other hand, in the method of the present invention, for example, the address of the defective dot only needs to be set in the counter, so that the correction throughput can be greatly improved.

Further, the result of the countermeasure is, for example, L of the arithmetic circuit.
If you change even the contents of UT, you can choose freely.
In other words, the measures to be taken by the laser device have only two degrees of freedom, that is, burning the circuit or sintering the circuit. Therefore, it is only possible to select whether the dot is permanently released or the dot is made conductive. Therefore, it was only possible to take measures against either the state of complete light emission (defective bright spot) or the state of no complete light emission (black point defect). However, in the present invention, any correction is performed depending on, for example, how to select an LUT. It becomes possible.

Further, the color value closest to the original color value of the pixel including the defective dot is displayed, or the color value closest to the average color value is displayed in consideration of the color values of neighboring pixels. By doing so, it is possible to greatly reduce the degree of interference remaining after the correction.

This also means that the correction according to the present invention can deal with a wide range of defects, can rescue a wide range of defective products that have been discarded conventionally, and has the effect of greatly reducing the overall defective rate.

As described above, according to the present invention, the improvement of the manufacturing technique or the countermeasures using a laser device or the like requires a considerable cost, which raises the overall cost and consequently the widespread use. There is an effect that cost can be significantly reduced as compared with the conventional countermeasure that has a problem such as hindering promotion.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating control of an applied signal to two adjacent dots of a defective dot in a display panel according to an embodiment of the present invention.

FIG. 2 is a graph showing visual spatial frequency characteristics.

FIG. 3 is an R1-G2 graph showing the relationship between the value of R1 and the corresponding optimal value of G2 when G1 = 0.

FIG. 4 is an R1-G2 graph showing the relationship between the value of R1 and the corresponding optimal value of G2 when G1 = 64.

FIG. 5 is an R1-G2 graph showing the relationship between the value of R1 and the corresponding optimal value of G2 when G1 = 128.

FIG. 6 is an R1-G2 graph showing the relationship between the value of R1 and the corresponding optimal value of G2 when G1 = 192.

FIG. 7 is an R1-G2 graph showing the relationship between the value of R1 and the corresponding optimal value of G2 when G1 = 255.

FIG. 8 is a G1-a (G1) graph showing a relationship between a value of G1 and a corresponding value of a gradient a (G1).

FIG. 9 is a block diagram illustrating a circuit configuration according to the embodiment.

FIG. 10 is a block diagram showing another circuit configuration according to the embodiment.

FIG. 11 is a block diagram illustrating a configuration of an arithmetic circuit according to the present embodiment.

FIG. 12 is a block diagram illustrating another configuration of the arithmetic circuit according to the present embodiment.

FIG. 13 is a diagram for explaining another example of control of an applied signal to a dot near a defective dot according to the present invention.

FIG. 14 is a diagram illustrating another example of control of an applied signal to dots near defective dots according to the present invention.

FIG. 15 is a G1-a (G1) graph for explaining another configuration example in which an approximate value is used as the slope a (G1).

FIG. 16 is a diagram illustrating a conventional failure situation.

[Explanation of symbols]

 Reference Signs List 101 red dot 102 blue dot 103 green dot 104 black matrix part 105 red defective dot 106 blue dot adjacent to defective dot 107 green dot adjacent to defective dot 301 address detection circuit 302 arithmetic circuit (control means) 303 switch circuit 304 display panel 305 delay circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/36 G09G 5/00 X 5C082 5/00 5/06 5/06 H04N 9/12 B 5/36 9/64 F H04N 9/12 G09G 3/28 K 9/64 5/36 520C (72) Inventor Yoichi Yamamoto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 2H093 NA06 NC50 ND49 ND53 ND60 5C006 AA22 AF51 AF53 BB11 EB03 EB04 5C060 AA05 BA02 BA03 BA04 BA07 BA09 BB07 BB13 BC01 BD02 BE05 BE10 DB00 EA08 EA10 HB25 HB26 HB27 JA22 5C066 AA03 BA20 CA17 DD04 EA03 GA02 EC01 GA04 KE02 KE03 KE04 KE09 KE18 KE24 KF05 KG01 KM13 KM14 KM15 5C080 AA05 AA10 BB05 CC03 EE28 EE30 JJ01 JJ02 JJ05 5C082 BA34 BA35 BB51 CA12 CA21 CB08 DA51 DA71 EA20 MM10

Claims (10)

[Claims] 1. A display device comprising a plurality of pixels, wherein each pixel performs a display operation with dots of at least three colors, in order to compensate for a display defect due to the presence of a defective dot that cannot be electrically controlled. A signal applied to a plurality of dots in the vicinity of the dot is formed such that a difference between a color obtained by the coloring of the plurality of dots and an original color based on the input signals of the defective dot and the plurality of dots becomes smaller. Control means for controlling the signal value to be applied to one of the plurality of dots, the original input signal of the defective dot, and the one dot in accordance with the input signal. After determining by calculation based on the function obtained from the correlation with the signal value to be applied to the other dots, the signal value to be applied to other dots is determined by calculation. A display device for. 2. An approximate straight line obtained from a correlation between an original input signal of the defective dot and a signal value to be applied to the one dot in accordance with the input signal is used as the function. The display device according to claim 1, wherein: 3. The color difference is determined by CIE (1976) L *.
3. The display device according to claim 1, wherein the color difference is represented by a * b * color difference value. 4. The method according to claim 1, wherein the control unit controls the plurality of dots so that a sum of luminances of the plurality of dots is substantially equal to a sum of original luminances based on input signals of the defective dot and the plurality of dots. The display device according to any one of claims 1 to 3, wherein a signal to be applied is controlled. 5. The display device according to claim 2, wherein the inclination of the approximate straight line is determined based on a value of an input signal of the one dot. 6. The method according to claim 6, wherein the slope of the approximate straight line is 0 and 1 /.
6. The display device according to claim 5, wherein an approximate value consisting of 2 ⁿ (where n is an integer of 0 or more) is used. 7. The first control means determines a slope of the approximate straight line based on a value of the input signal of the one dot, and calculates a value obtained by multiplying the slope by a value of the input signal of the defective dot. And a second circuit that adds a value of the input signal of the one dot to a value calculated by the first circuit, calculates a signal value to be applied to the one dot, and outputs the signal value. The display device according to claim 1, wherein the display device is a display device. 8. The display device according to claim 7, wherein said first circuit is realized by a bit shift circuit. 9. The control unit further calculates a signal value to be applied to the another dot, based on a predetermined value for each of the input signals of the defective dot and the plurality of dots, based on a predetermined value. Of calculating and multiplying
The display device according to claim 7, further comprising a circuit. 10. The display device according to claim 9, wherein said third circuit is realized by a look-up table.